Russia's surprise deployment of 200 troops to the Pristina airport on June 12 was part of a scheme to send into Kosovo a contingent of 1,000 or more men who could have tried to stake out a Russian zone in the northwest sector of the province, Western intelligence analysts have concluded.

The carefully planned operation was thwarted when the governments of Hungary, Bulgaria and Romania, prodded by the United States, denied Russian requests to use their airspace to fly more Russians into Kosovo.

When senior U.S. officials realized what the Russians had in mind, they lobbied the Eastern Europeans on overflight rights and began pursuing their Russian counterparts by telephone "at ungodly hours" on Sunday, June 13, according to one official. The Americans warned the Russians that their unilateral military moves risked obliterating the good will generated by their help in reaching a peace agreement.

Western analysts still dispute whether Moscow's intention was to seize a Russian zone in Kosovo or simply to send in more troops to strengthen Russia's hand in negotiating peacekeeping arrangements. Either way, the unilateral deployment of a large contingent would have caused "grievous harm to support for Russia" in Washington, said one senior State Department official.

The Russians nearly succeeded in adding to their forces on the ground, briefly winning permission from Hungary for six IL-76 military transport planes to fly over that country on June 11, before it was clear that the Russians were sending 200 men from their Bosnian peacekeeping force to the airport in Pristina, Kosovo's capital. But before those Ilyushins could get into the air, the United States asked Hungary to deny the Russians use of its airspace, and the Hungarians agreed, telling the Russians that only an act of the Hungarian parliament could grant overflight rights.

A reconstruction of the events surrounding the Russians' unexpected deployment into Kosovo, based on reporting in Washington, Moscow and Brussels, indicates that the Russian operation was thoroughly planned, deliberately deceptive and considerably more ambitious than its accomplishments would suggest. Many questions remain about who in Moscow was in charge of the decision-making that led to the operation.

When the NATO allies realized, late on June 11, that the Russians were moving men toward Pristina, Gen. Wesley K. Clark, the NATO commander, speedily devised a plan to deploy NATO troops by helicopter to the Pristina airport, creating the possibility for the first NATO-Russia confrontation since the end of the Cold War. But British Gen. Michael Jackson, head of the peacekeeping force, argued that such a move would upset the delicate arrangements he had negotiated with Yugoslav officers on their withdrawal from Kosovo, and Clark's plan was dropped.

In Moscow, Russian generals were openly frustrated at their inability to complete the deployment.

"When the Russian military saw how popular their first little glorious victory was," said one senior U.S. official, referring to the arrival of the 200 troops at Pristina's airport, "the effort to score again [with additional deployments to Kosovo] became more intense, and more important from their point of view. If they'd been able to keep on going, you could have had a very serious breakdown in confidence, and maybe in our ability to organize a peacekeeping effort in Kosovo."

Western officials are still debating the Russian moves, wondering both why the Russian military took the risks it did and what role President Boris Yeltsin played in the decisions.

Senior intelligence analysts in Washington have concluded that there was a strong consensus among Russian officials in Moscow, including Yeltsin, that Russian troops had to play a role in Kosovo after Yugoslav President Slobodan Milosevic accepted peace terms. One official said Yeltsin agreed in general terms that Russian troops would have to be deployed in Kosovo at least as soon as NATO forces were. "Whether he [explicitly] approved the idea of going in first, we aren't sure," this official said.

In Moscow, Russian sources said Yeltsin did approve the deployment in advance, during a telephone conversation with Gen. Anatoly Kvashnin, chief of the Russian general staff.

Russian military officials have boasted that the deception involved in the Pristina airport operation was deliberate. "The operation was very carefully prepared," Gen. Georgi Shpak, commander of Russia's paratroopers, told a Russian newspaper. "The main difficulty was to hide the fact that the operation was being prepared."

One question is the degree to which Yeltsin, frail and ill, participates in detailed discussions of complex issues. Western intelligence analysts and many Russian sources say his involvement is minimal.

In late April, Yeltsin complained in a closed meeting of his national security advisers about Russia's inability to influence the Yugoslav war. "Why are they not afraid of us?" he lamented, according to a source in Moscow. His generals had no answer.

Western nations were alarmed when the Russians moved into the Pristina airport, though not afraid of the small force of 200. Within two weeks the British were providing food and water for the isolated contingent.

But Clark took the Russian deployment seriously, which led to his plan to dispatch U.S. troops by helicopter to the airport. Defense Secretary William S. Cohen and Gen. Henry H. Shelton, chairman of the Joint Chiefs of Staff, supported Clark's plan. But Jackson and the British government demurred, and Russian Foreign Minister Igor Ivanov assured U.S. officials that the Russian force moving toward Kosovo would stop before it crossed into the province.

The Russians' premature arrival in Pristina despite Ivanov's assurance complicated the diplomatic exchanges over the peacekeeping arrangements. The Russians insisted that they be given a separate sector within Kosovo, contributing to the conclusion of some Western intelligence analysts that they had intended to establish such a sector unilaterally. Other Western officials argued that the Russian goal was to create a presence on the ground as a bargaining chip.

The negotiations sharpened U.S. officials' questions about who was in charge in Moscow. At the meetings in Helsinki to decide on Russia's role in the Kosovo peacekeeping operation, U.S. officials perceived open disagreements between Russia's civilian and military officials. They also saw manifestations of the splits within the Russian military. Marshal Igor Sergeyev, the defense minister, is regarded skeptically by many of his colleagues, according to Russian sources. Several sources said Sergeyev may not have been told by Kvashnin, his chief of staff, about the surprise move to Pristina's airport.

An especially problematic figure for the Americans was Gen. Leonid Ivashov, a former Communist Party commissar in the old Soviet Army who runs the Russian Defense Ministry's international cooperation department. Ivashov is a long-time hard-liner who has admitted that he agitated in favor of a military coup against Mikhail Gorbachev in 1990 and who is clearly skeptical of any Russian cooperation with NATO.

In the Helsinki negotiations, U.S. officials said, little progress was made until Cohen drew his Russian counterpart, Sergeyev, into private meetings from which Ivashov was excluded. Even then, disagreement persisted on whether Russia would have its own sector in Kosovo.

Yeltsin announced last Friday that he had firmly instructed Sergeyev to win approval for a separate Russian zone, saying he "categorically does not agree" with the idea of Russian troops patrolling sectors controlled by other countries. But several hours later, for reasons still not clear to the non-Russian participants, the Russians agreed to a plan that dispersed their troops through the British, French, German and American sectors, with no zone of their own.

At the end of the long negotiations, Sergeyev and Ivanov said they had to make one last phone call to Yeltsin for his approval of the final deal. They adjourned to the Russian Embassy in Helsinki, then came back to accept the arrangements. Had they spoken personally with Yeltsin? "They said it was Yeltsin," according to one U.S. negotiator.

Correspondent William Drozdiak in Brussels and staff writers Bradley Graham and John F. Harris in Washington contributed to this report. Hoffman reported from Moscow.